Colonial buckle- but what type?

[DownNDirty]

Found at the site of a plantation dating back to the 1670's. It's only 1 inch X1 1/8" and has a curvature. I was thinking possibly knee buckle?

 

[sutphin]

DND NICE COLONIAL BUCKLE. NOT SURE USE OR TIME BUT SURE IS NEAT ....

 

[DownNDirty]

Here it is all cleaned up; it's either pewter, silver plated or silver. Probably pewter. Any ideas as to age & type of buckle?

 

[DownNDirty]

Here's the picture